A graduate of the University of Uppsala, Sweden, Bertil Lindblad directed the Stockholm Observatory from 1927-65. He often visited the California observatories. He extended spectroscopic means of distinguishing between giant and main sequence stars, and he studied the structure and dynamics of star clusters. His most important work was the theory of galactic rotation. He showed that the system of stars can be divided into several subsystems rotating about the same axis, each subsystem having its own rotation rate and consequent degree of flattening. The “high-velocity” stars are actually moving slowly; the sun is moving faster. Lindblad confirmed Harlow Shapley’s direction and approximate distance to the center of the Galaxy, and he estimated the galactic mass and the period of the sun’s orbit. His work led directly to Jan Oort’s theory of differential galactic rotation. Lindblad headed several national and international organizations and was one of the organizers of the European Southern Observatory.